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UNITED y STATES PATENT; OEEIcE.

HENRY J. HARRISON, OF LIVERPOOL, COUNTY OF LANCASTER, ENGLAND.

COLUMN, SHAFT,` GIRDER, 4am. Y

SPECIFICATION forming' part of Letters Patent No. 256,478, 'dated April18, 1882-.

Application led November 8, 1881. (No model.) Patented in England March4, 1881.

To all whom it may concern:

Be it known that I, HENRY JAMES HARRI- SON, of Liverpool, in the countyof Lancaster,

England, have 'invented certain new and useful Improvements in Oolumus,Shafting,Gird ers, Piers, Masts, Spars, Posts, and other likestructures; and I do hereby declare that the following` is a full,clear, and exact description ofthe inventiomwhich will enable othersskilled.

in the art to which it appertains to make and use the same.

This invention consists essentially in giving to the metal structure acore of wood firmly secured to the metal throughout the entirecontact-.surface or at the ends, so as to preventthe one moving 011 theother, and enable the wood to form not merely a tension memberinagirder,

, but by its superior elasticity to hold the column, shaft, or beam inposition after the iron has snapped by a. sudden blow or strain.. Up tothe present time wooden girders have been strengthened by having a barof iron fastened to them by screws, and have frequently in roofs beenmade the compression member with a tierod to take the tensile strain;but I am notawarethat a metalgirder, shaft, or other like structure anda wooden core have heretofore been combined and united as hereinexplained.

In vertical piers or columns and other struts Vrequiring to withstand alongitudinal compressive strain with occasional or constant sidestrains-such as the piers ofa bridge- I secure the core to the ironcolumn at each end, so that it can form a tension member of the girder,while at the same time it` lls up the hollow center, and thus preventsin great measure a collapse of the structure.

The way in which I secure the core to the iron column, girder, or shaftis to place the core loosely in the iron shaft and then completely tillthe interstices with melted pitch or any biact-ing mainly as a tensionmember. I have not yet calculated or found from experiment thecomparative thicknesses of iron and wood that give the best results, butwould state that ,the best results will probably be obtained, providedthe pitch be sufficiently adhesive,when the tensile strength of thewood, taken as a whole, equals at least half the compressive strength ofthe iron column. In this way the thickness of iron for any givendiameter of column can be calculated from the ordinary tables ofstrength of materials. Furthermore, the wood is madeA to project beyondthe iron-work, as shown in Figures 1 and 2,'into the pier-and into thesuperstructure,into each of which itis firmly secured. n l In the caseof girders the core-is preferably firmly secured into the next. girderor abutment, so as to make a continuous girder to some extent, as shownin Fig. 3. l The object of this .core is not merely to strengthen thecolumnor girder, which it does to a remarkable and altogether unexpectedextent, but should the iron-Work of the girder be cracked with a suddenstrain or side blow,the wooden core remaius'to keep the broken pieces inposition.

In employing my invention for shafts I prefer to drill holes rightthrough the wood and iron at intervals of, say, half or a third of thevdiameter, and in various directions perpendicular to the axis of the.shaft, and place therein 'closely-fitting boltsi securely screwed up.

These assist the pitch in preventing the iron from moving on the wood.

It' there be any fear ot' damp getting into the wood, especially wherethe structure is to be placed in Water, it is best either to entirelyfill the pores of the wood with hydrocarbonaceous or silicious matterunder pressure, or saturate them with moisture before inserting the corevin the pillar, and, then prevent the water from evaporating out byincrusting the outer surface well with pitch and placing itin itsposition as soon as possible. Theobject of this is that if the wood beinserted perfectly dry and is then allowed to imbibe moisture it is aptto strain or fracture the iron-work inclosing it. The kinds of woodIprefer are rocke1m,oak, greenheart, and teak 5 butother Woods will donearly as well.

.In adapting the invention to ships spars, as

Vest# f IOO - as shown.

the main strain comes upon the central part of the spar, I only incasethis part, as shown in Fig. 6. The pitch in this case should be assistedby putting bolts through atintervals as in shafts, and for columns,masts, spars, &c., exposed to the full glare of the sun or the heat oftropical regions, pitch or asphalt of a high melting-point should beemployed, and where practicable should be assisted by bolts or otherfastenings, so that the entire strain should not fall upon the pitch,but should be taken up in part and the iron and wood prevented frommoving upon each other by metal fastenin gs, especially at and near theends, in addition.

My invention can even be used in ships, tubular bridges, and shipshulls, which are really girders, only in these cases, as of course theentire tube or hull cannot be filled up like a small girder, thecellular spaces in the top and bottom members of the tubular bridge andthe space between the outer and inner skin of a ship are utilized forthis purpose.

Although the invention can be well understood from the foregoingdescription without drawings, I have added the accompanying` diagrams toillustrate it more eftectually. In these, Figs. l and 2 are views of abridge crossing a broad, shallow stream, in which the timber cores areseen built into the piers. In practice a hole is left in the pier forthe tim ber, and after the core is inserted hot pitch or as phaltmingled with stone chippings is poured and rammed in till all the interstices are filled. The upper part oi' the column carries the cap fromwhich the tension-bars are hung. This cap is placed round the wood coreand bolted to the sleeper. Figs. 3,4, and 5 show a trestlebridge builtovera valley usually dry and where a side pressure is not so likely tobe expected. This shows the continuous wooden core inside the irongirder, which has been broken away for the purpose. Figs. 6 and 7 show amast, spar, and hull-bottom formed on my principle. The space betweenthe ribs ot the ship I till up with wood lagging or composition of anykind. Over this I place the beams,laid longitudinally close together anddoweled together, I then thoroughly saturate the whole with hot pitchand apply the inner skin, bolting the whole together; or, instead, Ibuild the whole up, as shown, and then force in the hot liquid pitch,after first heating the two iron shells in any convenient manner. Fig. 8shows a screw-shaft made on this principle; Fig. 9, one made on theprinciple of an Armstronggun, built up of coils, but with a wooden coreFigs. 10 or 11, section of same; Fig. l2, pillars for mills, warehouses,Sac., made on my principle. The advantage of these is that if a re takesplace theiron columns cannot bend and snap with the heat, as they do atpresent, the wood holding them upright.

ll am aware that piers and like structures have hitherto been formedwith acentral wooden core driven into the earth or bed of the water-basin and surrounded by a metallic sheathing or casing, the interveningspace being filled with concrete; but I am not aware that the metal andthe wood of a compound structure such as herein described and shown havehitherto been cemented together so as to prevent the movement of oneupon the other.

I am also aware thatit is not new to employ a wooden strengthening' orstiitening core in a metalliccolumn or like structure, and that lightStrips suitableto receivelath and flooring nails, bntof insuflicientstrength to materially assist in supporting weight or strains,have beencombined with and spiked or bolt-ed to metallic licor-beams.

I claim as my inventionl. In a column, beam, or other structure,substantially such as described, the combination of a metallic body orcasing and an internal wooden core secured to the metal throughout itslength by a strongly-adhesive cement, and

adapted to carry a material portion ot the weight or strain to which thestructure is subjected. l

2. A hollow metallic column, shaft, girder, mast, strut, stay, post,pole, spar, or like structure, in combination with an internal core ofwood, drmlycemented to the same bya strongly-adhesive tough pitch orasphalt introduced in thc liquid state and setting hard, substantiallyas described.

3. A hollow metallic column, shaft, girder, strut, stay, post, or likestructure, provided with an internal core ot' wood projecting bc youdthe end of the metal and firmlycemented to the metal, substantially asand t'or the purpose explained.

4. A hollow metallic structure,substantially such as shown anddescribed,having a wooden core lling its interior, and held therein bystronglyadhesive cement and trails verse bolts,

as set forth.

5. The mode of attaching internal wooden cores securely to hollowmetallic structures, consisting in heating the iron structure to a heatbarely sufficient to char the wood, and

then pouring in melted pitch or asphalt, so as.

to till up all the intcrsices and securely cement the core to themetallic structure.

6. The iron girders filled with wooden planks or beams, breakingjointwith each other, and having the interstices iilled up with cementingmaterial, substantially as described.

HENRY JAMES HARRISON.

Witnesses J. OWDEN OBRIEN, HY JONES.

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